I have put the 1 1/2 inch spacer between the XLRF back and the Film back. I am trying for a macro capability and I got it. Short of using my focus back then switching to my film back is there any good way of converting marked lens focus distances to "spacer" focus distances. (Right now, I just put on the ground glass and move in and out until I get a focus, set my tripod, mount the camera, move the tripod in and out until the focus is what I want, change to a film back, then shoot. I am thinking of just tying a premeasured string to the camera and setting the camera while holding the string on the subject. Has anyone used these body spacers? PS The photos are incredibly good, so it's worth the hassel. thanks

And the Answer is a macro focusing rail. Since I have a macro bellows for my 35mm, you would think that I would have thought of the straight rail focusing mount. Thanks for the answer. Is there a standard formula for shifts in the focusing distances when the lens to film plane distance is increased? I have magnification change tables (ie the 1 1/2 spacer is about 40 mm or 1/2 the lens focal length so my magnification ratio should be about 1:2. I will need the 3.5 inch spacer to get to a true 1:1) What happens to the focal length of the lens is a mystery to me. The focus goes down to about 18". If I go to a 3.5" spacer will the subject to lens "in focus" distance drop again? (ie down to 2"). I know I should know this and I guess I can recon the Macro Sites for an understandable answer, but, sometimes you all seem to "know" the answer that applies to our equipment. thanks for the help.